In order to reduce pollution of current harmonic and reactive power generated by an electric device to the power grid, the current harmonic of the electric device needs to meet certain harmonic standards. In order to meet the harmonic standards, the electric device needs to carry on power factor correction (PFC for short). In this context, various power factor correction technologies have been proposed and applied to the electric device.
The interleaved PFC solution is receiving more and more attention because of small harmonic current and high reliability. The current interleaved PFC solution usually uses a two-way symmetrical boost-type circuit structure. Although the circuit structure is symmetrical, it may still cause current imbalance of the two-way symmetrical boost-type circuit structure because of component differences such as differences between inductors, resulting in too large current of one switch tube. When the current of the switch tube reaches a certain level, it may burn out the switch tube, making the whole circuit failure. Therefore, the interleaved PFC solution also carries on current balance control on two switch tubes in addition to carrying on the power factor correction.
In the related art, two following solutions are proposed to realize the current balance control on the two-way switch tubes. The first solution proposes a power factor correction device for sampling a total current of the two-way symmetrical boost-type circuit, and a current of one circuit in the two-way symmetrical boost-type circuit. The power factor correction device uses a difference between the total current of the two-way symmetrical boost-type circuit and the current of the one circuit in the two-way symmetrical boost-type circuit as an estimated value of the other one circuit in the two-way symmetrical boost-type circuit, and carries on the current balance control on the two-way switch tubes based on the estimated value. The second solution proposes an interleaved PFC solution for sampling currents on the two switch tubes respectively. This solution may calculate a duty ratio of the switch tube and achieve current balance without sampling the total current of the two-way symmetrical boost-type circuit.
However, both of the above-mentioned related technologies require at least two current sensors to realize the interleaved PFC solution for performing the current balance on the two switch tubes. Therefore, the circuit cost is high.